Digital High Sensitivity Microbarometer - Real Geophysics Research on a budget

...project under active development ....

This project complements our infrasound monitor. A microbarometer with approx 1Pa resolution and 0.4Pa noise threshold based on the digital ICP-10125 i²c enabled absolute pressure sensor. The sensor is interfaced with a Raspberry Pi providing signal processing, saving data in .mseed format, plotting and then uploading plots here. System has performance of research/professional systems at a fraction of the price. A full rig, premounted sensor and a Raspberry Pi costing approx £70.

Presently using the sensor premounted on a board from Pinimori. If things go well I may look into producing a board to carry multiple sensors to reduce noise.

To Do

• Code rolling previous 24hr plot.
• Check for stability.
• Read & plot from onboard temperature sensor (0.4^oC precision).
• Calibrate?

Student Extension

Soldering up the sensor board is trivial though installing Linux on the Pi and required python libraries is not. A school can then register their station with the International Seismological Centre.

Getting the system to run is a good short term goal. Longer term though one would want to construct an outdoor station. Whilst the system will register well in a roof space ideally one wants an outdoor sensor head - easily connected to a RPi indoors via a 2 wire line. This would allow one to access the temperature probe permitting richer environmental readings and the interesting correction of pressure readings to a comparable one at sea level.

• Build and test a waterproof outdoor housing.
• Correct to pressure at sea level using altitude & temperature?
• Code to trigger alert at unusual events.

Live Microbarometer, Guisborough, UK
Rig Alpha: Loftspace - under pitched tile roof - 5Hz sampling - 30s rolling average

nb: quoted are absolute pressures at ~120m above sea-level. For reading at sea level add ~14.3 hPa.

Archived plots

We have already implemented a infrasound monitor using a differential pressure sensor with a resolution of approx 1/20 Pa. This is very sensitive to short term changes in pressure, i.e. those occuring over less than 200sec but at the cost of monitoring longer term changes. It is difficult to get such resolution from an absolute pressure sensor hence this device.

As an example the Tonga pulse's arrival in the UK was measured by two Met Office's microbarometers at ~2hPa i.e. 200 Pa. This absolute pressure sensor, with a resolution of ~1Pa should have easily been able to detect this and similar signals.

https://twitter.com/metoffice/status/1482605906659622914

The above are simple daily and weekly data plots. These are generated on the fly by the Pi used to monitor the sensor, and should be used for quick observation of output. The idea being that the data be downloaded from the PI for more detailed analysis.

page updated 3/07/23